Hydrodynamic power drives

ABSTRACT

A controllable filling fluid coupling has outlets at the radially outer part of its working circuit periphery for the removal of a cooling flow of working liquid fed into the working circuit when the input is shut down and the output is rotated by the load which is driven from another source of power. The outlets have collecting scoops which face into the vortex which is set up under these conditions. Under normal driving conditions, the liquid in the vortex travels in the opposite direction, i.e. from the input member to the output member at the outer periphery and is not intercepted by the collecting scoops.

United States Patent 1191 Bilton July 24, 1973 HYDRODYNAMIC POWER DRIVES3,486,336 12/1969 Bilton 60/54 t [75] lnven or .lliolhllialgzllton,Walton on Thames, Primary Examiner Edgar w Geoghegan g Attorney-RaywoodH. Blanchard I [73] Assignee: Fluidrive Engineering Company Limited,lsleworth, Middlesex, 57 ABSTRACT England A controllable filling fluidcoupling has outlets at the [22] Filed; Feb, 16, 1972 radially outerpart of its working circuit periphery for the removal of a cooling flowof working liquid fed into [21] Appl' 226776 the working circuit whenthe input is shut down and the output is rotated by the load which isdriven from an- 52 us. (:1. 60/351, 60/DIG. 5 other source of p TheOutlets have collecting [51] Int. Cl. Fl6d 31/10 Sc00pS which face intothe Vortex which is Set "P under [58] Field of Search 60/54, DIG. 5these conditions Under normal driving conditions, the liquid in thevortex travels in the opposite direction, Le. [56] Referen s Cit d fromthe input member to the output member at the UNITED STATES PATENTS outerperiphery and is not intercepted by the collecting 2,534,517 12 1950Jenny 60 54 Scoops 2,841,959 7/1958 Snow 60/54 9 Claims, 10 DrawingFigures 1 HYDRODYNAMIC POWER DRIVES (hereinafter referred to as the kinddescribed) are fluid couplings and torque converters.

The invention is concerned with the problems which arise when the inputmember is stationary and the output member is rotated. This situationcan arise for example when two (or more) power units each drive a commonload through its individual power drive and one of the power units isshut-down for maintenance while the other power unit continues to drivethe load. Even though the shut-down power drive is drained of itsworking fluid, the air left within the working circuit will itself actas a working fluid to the extent that a torque is transmitted from theoutput member (which is rotating at the loadspeed) to the stationaryinput member. The shut-down power drive is then operating under theequivalent of 100 percent slip and absorbs appreciable power (sometimes)known as windage losses) all of which is dissipated within the workingcircuit in the form of heat. In the case of high power, and especiallyhigh speed, installations, the heat generated is considerable. Often,to'remove this heat, a small liquid flow is passed through the workingcircuit of the shut-down powerdrive. Whilethis can carry away heatgenerated within theworking' circuit, it itself increases the torquetransmitting characteristics of the working circuit and thus increasesboth the heat generated within the working circuit and the drag torquewhich is added to the load driven; by the other. prime movers.

Except where the cooling liquid flow is so mall as to have negligiblecooling effect, these effects of the introductionof the cooling flowtend to be accentuated since the'usual means for removing liquid fromthe working circuit (such as leak off nozzles and scoop tubes) rely onrotationof-the inputmember and the casing structure which rotates withit..Thus, when the input member is stationary, the cooling flow tends toaccumulate within the workingcircuit.

Another example arises in the case of marine drives using a dieselengine driving'a propeller shaft through .a hydrodynamic drive such as afluidcoupling for normal and maneuvering drives, the-marinedrive alsoincorporating a gas turbine which takes over the drive to thepropellershaft under high speed conditions. In such an arrangement, thegas turbine is connected to the propeller by a one-way clutch; when theturbine shaft speed rises above afpredeterrninedvalue, the one wayclutch engages and the-hydrodynamic drive between the diesel engine andthepropeller shaft is emptied of its working fluid. The propellershaftspeed then rises above the maximum working speed produced by thediesel engine when working without assistance from the gas turbine. Thediesel engine is working without load and is therefore stopped while theoutput member of the hydrodynamic drive is rotated by the gas turbine ata speed which may be twice that at which it is rotated when the dieselengine is driving'the propeller shaft. With this arrangement, it will beappreciated that the windage heat generated in the hydrodynamic drive isparticularly serious.

In accordance with the present invention there is provided acontrollable-filling hydrodynamic power drive comprising circuitelements, including an input element and'an output element, the circuitelements defining a toroidal working circuit into which a'flow ofcooling liquid can be fed when the input element is stationary, whereinthe boundary wall of the working circuit includes one or more outletsprovided with collecting scoops facing into, for interception of, thatvortex flow I which is set up within the working circuit when the outputelement is rotating, the input element is stationary and a flow ofcooling liquid is supplied to the working circuit.

With this arrangement, the desired cooling flow can be passed throughthe working circuit when the input is stalled without resulting in abuild-up of cooling fluid within the working circuit and consequentincrease in heat generation and drag torque.

When the output is rotating at a faster speed than the input, the fluidin the vortex travels around the axis of the hydrodynamic drive in thesame direction as when the input is rotating faster than the output.However, the direction in which the fluid travels between the input andoutput elements is reversed. Thus, the scoops are inactive when theinput is rotating faster than the output, i.e. under normal drivingconditions.

Preferably, the input element and the output element are adjacent eachother at the radially outermost portion of the working circuit and thecollecting scoop or scoops is/are located in this portion of the workingcircuit. The scoop or scoops are then advantageously positioned in theinput member.

By way of example, the application of the invention to fluid couplingswill now be described by way of example with reference to theaccompanying drawings, in which:

FIG. 1 is an axial sectional view of a single circuit fluid coupling, I1

FIG. 2 shows a detail of FIG. 1 on an enlarged scale,

FIG. 3 is a section on the line IIIIII of FIG. 2,

FIG. 4 is a section on the line IVIV of FIG. 3,

FIG. 5 is a perspective view of an end of the tube shown in FIGS. 2 to4,

FIG. 6 is a view corresponding to FIG. I of a doublecircuit fluidcoupling,

FIG. 7 shows a detail of FIG. 6 on an enlarged scale,

FIGS. 8 and 9 are sections respectively on the lines VIII-VIII and IVIVof FIGS. 7 and 8, and

FIG. 10 is a perspective view of an end of the tube shown in FIGS. 7 to9. I g

The fluid coupling shown in FIG. 1 has an input driving huh I carryingan'impeller casing 2 whichis flanged to an impeller element 3 and ascoop chamber casing fine a toroidal working circuit W whichcommunicates No. 18571/67. The quantity of working liquid in the workingcircuit W at any instant is controlled by an adjustable trimming scoop(not shown) which trims off liquid from the scoop chamber in aconventional manner.

Working liquid can pass from the working circuit W to the scoop chamberS through tubes 12 mounted in passages formed in the impeller adjacentthe radially outermost portion of the working circuit W. Theconstruction of the tubes 12 is shown in detail in FIGS. 2 to 5. One end13 of each tube 12 is cut away on one side at 14 so that the entry 15 tothe tube 12 from the working circuit has a back wall 16 carrying asegmental plate 17 which is welded on to the curved back wall portion 16of the tube and forms a scoop.

When the impeller element 3 and the impeller casing 2 are heldstationary while the output shaft and runner 8 are rotated by the load,which is now being driven by some other source, a small cooling flow ofworking liquid still has to be supplied to the working circuit W throughthe inlet 9 and inlet ports 11 in order to carry away the heat generatedby windage losses caused by the air vortex set up within the workingcircuit W. The cooling liquid itself tends to follow a vortex pathwithin the working circuit W and accordingly has open and direct accessto the tubes 12. In this way, the working liquid fed to the workingcircuit W for cooling purposes is continuously removed from the workingcircuit to the scoop chamber from which it leaves through sealedlabyrinth L. Under these conditions, this action is assisted by thescoop l6 and particularly its extension 17 which together form ascooping orifice for liquid travelling in the general direction of thearrow 19 (FIGS. 3, 5).

The coupling shown in FIG. 6 is of the double working circuit typehaving two working circuits W1 and W2. The impeller casing 22 carriestwo vaned impellers 23 and 24 while the output shaft 25 carries tworunners 26 and 27 back-to-back. The working circuit W1 is definedbetween the impeller 23 and the runner 26 while the working circuit W2is defined between the impeller 24 and the runner 27. The workingcircuit W1 is supplied with working liquid from a conduit 28 andcollecting ring 29 through inlet ports 30 while the working circuit W2is supplied with working liquid from a conduit 31 and collecting ring 32through inlet ports 33. The quantity of working liquid in the workingcircuits is controlled by a trimming scoop (not shown) working in ascoop chamber S, the trimming scoop serving to remove excess workingliquid supplied through the inlet ports 30 and 33 thus maintaining acooling flow of oil through the working circuits in conventional manner.

Each of the impellers 23 and 24 has a flange 25 and 26 respectively atits radially outer periphery. The radially outer portions of theseflanges are used for bolting the flanges to the casing 22 while theradially inner portions of these flanges accommodate tubes 27 whichserve to remove working liquid from the respective working circuits whenthe casing 22 is stationary and the output shaft 25 and runners 26 and27 are still being rotated by the load to which the output shaft 25 iscoupled.

In order to prevent loss of working liquid through the tubes 27 from theworking circuit W2 under normal working conditions, that is when thecasing 22 is rotating and the coupling is driving the output shaft 25,the

casing 22 carries an annular end section 34. When the casing 22 isrotating at its normal working speed, the centrifugal head is generatedin the space between the end member 34 and the impeller 24 and this headopposes loss of working liquid through the tubes 27 from the workingcircuit W2. When however the casing 22 is stationary, there is nocentrifugal head opposing the removal of liquid from the working circuitW2 by the tubes 27.

A suitable form for the tubes 27 is shown in FIGS. 7 to 10. As seen inFIGS. 6, 7, 9 and 10, the portion of each tube projecting from itsflange 25 or 26 is cut away at an angle of 45 at 41 to conform generallyto a correspondingly shaped shoulder 42 on the casing. In addition, asshown in FIGS. 8 and 10, one half of this projecting portion is cut awayat an axial plane of the tube which also passes through the axis of thecoupling. The resulting portion 43 acts as a scoop to collect workingliquid and feed it into the tube 27 when the casing 22 is stationary andthe output shaft 25 is rotated by the load, while a cooling flow ofliquid is passed through the working circuits.

It will be noted that in the coupling shown in FIGS. 6 to 10, the tubes27 lie wholly outside the working circuits W1 and W2 whereas in theconstruction shown in FIGS. 1 to 5, the tubes 12 project into theworking circuit at its outer profile diameter thereby marginallyreducing the overall external diameter of the coupling assembly.

In order to assess the effectiveness of the tubes 12 (FIGS. 1 to 5) and27 (FIGS. 6 to 10), tests were carried out with the impeller assemblyheld stationary. The runner assembly was then driven at various speedsand a cooling flow of working liquid was suplied to the coupling. Ingeneral, it is found that in fluid couplings the horsepower input to thecoupling is equal to K multiplied by the fifth power of the diameter ofthe working circuit in meters and by the cube of the input speedmeasured in hundreds of revolutions per minute, K being effectively adimensionless constant.

Tests were carried out first of all with a coupling of the kind shown inFIG. 1 without the scoop tubes 12. The drive-back torque was measured atthree speeds, a high speed corresponding to percent of full workingspeed and at low and extra low speeds corresponding to 20 and 5 percentrespectively of full working speed. It was found surprisingly that K forsuch an arrangement was not dimensionless since it varied with therunner speed. Supposing that the actual value K equals k X K where K isthe valve of K for the original design at the high speed, then it wasfound that the values of k, at the high, low and extra low' speeds wererespectively 1.00, 3.63 and 7.37. During these tests, it was observedthat the cooling oil was being ejected through the bore of the scoopchamber S and out through the labyrinth system indicated generally at Lin FIG. 1. In an attempt to assist'this ejection of the cooling oil, andthereby reduce the value of k, and hence of K, the radial clearancebetween the scoop casing bore and the stationary manifold formed by thepassage 9 was increased from 0.00l5D to 0.0l4D and k was then determinedfor the high, low and extra low' speeds obtaining values of 0.96, 2.91and 2.09. It was thus apparent that significant improvement was onlyobtained at lower speeds by this measure.

The tubes 12 were then installed in the coupling, and the values of kagain determined at the three speeds and were found to be respectively0.19, 0.80 and 0.14 representing a substantial reduction in the driveback torque at all three speeds. In order to confirm the importance ofthe orientation of the scoop ends of the tubes 15, further values of kwere determined with the v runner driven in the opposite direction ofrotation.

These values were respectively 1.95, 3.63 and 3.41, thereby confirmingthe importance of the orientation of the scoops. TI-Ie results aresummarized in Table I, the size of the cooling oil flow being small,i.e. the ratio of gallons per minute through flow to total gallonsrequired to fill the working circuit was about 25 percent.

TABLE I Values of khd I Runner Speed High Low Extra Low Original Design1.00 3.63 7.37 Large Scoop Chamber/Manifold clearance 0.96 2.91 2.09Large clearance plus Scoop Ended Tubes: 0.80 0.14 Large Clearance plusScoop Ended Tubes. Runner Driven in Opposite direction 1.95 3.63 3.41

SImilar tests were carried out with another fluid coupling of differentmechanical design, and the following results (Table Ila were obtainedfor a small cooling oil flow (about 30perce nt) and a large cooling flow(Table IIb) of about 170 percent (again measured in gallons per minute)with a percentage of the working circuit capacity. In this instance, thevalues of k are tabulated, k having the same significance in these testresults as the factor k in the previous investigation. With thiscoupling, a further test was carried out with the scoop ended tubes, andwith the oil escape path from the scoop chamber bore restricted, toascertain whether this had any influence on the results already obtainedwith this design.

Tabulations of Values of k TABLE 11(a) Small Cooling Oil Flow Casingclosed in 'TABLE 11(b) Large Cooling OilFlow Runner S eed High Low ExtraLow Original esign 2.08 14.5 1 l8 Scoop Ended Tubes: 1.50" 6.92 75.9Scoop Ended Tubes and Scoop Casing closed in 1.67 8.08

It will be seen from theseresults that the scoop ended tubes areeffective at both small and large coolingoil flows in reducing'the driveback torque, and that closing the opening at the scoop chamber casingbore has little effect at the low and high speeds.

If desired, some of the tubes 12 or 27 may have their scoops facing inthe opposite direction to the others. Thus, alternate scoops could facein opposite directions to cover the various modes of maneuvering in amarine transmission while giving identical ahead and astern couplingconstructions. When the direction of drive is reversed, an equal numberof scoop orifices are still facing into the new direction of vortexflow, thereby keeping the working circuit substantially empty.

I claim:

1. A controllable-filling hydrodynamic power drive comprising circuitelements, including an input element and an output element, the circuitelements defining a toroidal working circuit into which a flow ofcooling liquid can be fed when the input element is stationary, whereinthe boundary wall of the working circuit includes one or more outletsprovided with collecting scoops facing into, for interception of, thatvortex flow which is set up within the working circuit when the outputelement is rotating, the input element is stationary and a flow ofcooling liquid is supplied to the working circuit.

2. A hydrodynamic power drive according to claim 1, wherein the inputelement and the output element are adjacent each other at the radiallyoutermost portion of the working circuit and the collecting scoop orscoops is/are located in this portion of the working cir cuit.

3. A hydrodynamic power drive according to claim 1, wherein the or eachscoop comprises a tube cut away at one side to leave the other sideprojecting.

4. A hydrodynamic power drive according to claim 3, wherein theprojecting side of the or each tube carries an end wall.

5. A hydrodynamic power drive according to claim 1, wherein the inputelement and the output element are adjacent each other at the radiallyoutermost portion of the working circuit and the collecting scoop orscoops is/are located in this portion of the working circuit and the oreach scoop comprises a tube cut away at one side to leave the other sideprojecting.

6. A hydrodynamic power drive according to claim 5, wherein the or eachcollecting scoop is mounted in the input element at a gap between theinput and output elements.

7. A hydrodynamic power drive according to claim 6, herein the end ofthe collecting scoop is adjacent an inner wall surface of an inputelement casing structure.

8. A hydrodynamiopower drive according to claim 1, wherein each outletdischarges into a tube or chamber leading into a radially inner portionof a casing structure which rotates with the input element.

9. A hydrodynamic power drive according to claim 1, having a pluralityof collecting scoops wherein some of the collecting scoops face in theopposite direction of rotation to the other collecting scoops.

1. A controllable-filling hydrodynamic power drive comprising circuitelements, including an input element and an output element, the circuitelements defining a toroidal working circuit into which a flow ofcooling liquid can be fed when the input element is stationary, whereinthe boundary wall of the working circuit includes one or more outletsprovided with collecting scoops facing into, for interception of, thatvortex flow which is set up within the working circuit when the outputelement is rotating, the input element is stationary and a flow ofcooling liquid is supplied to the working circuit.
 2. A hydrodynamicpower drive according to claim 1, wherein the input element and theoutput element are adjacent each other at the radially outermost portionof the working circuit and the collecting scoop or scoops is/are locatedin this portion of the working circuit.
 3. A hydrodynamic power driveaccording to claim 1, wherein the or each scoop comprises a tube cutaway at one side to leave the other side projecting.
 4. A hydrodynamicpower drive according to claim 3, wherein the projecting side of the oreach tube carries an end wall.
 5. A hydrodynamic power drive accordingto claim 1, wherein the input element and the output element areadjacent each other at the radially outermost portion of the workingcircuit and the collecting scoop or scoops is/are located in thisportioN of the working circuit and the or each scoop comprises a tubecut away at one side to leave the other side projecting.
 6. Ahydrodynamic power drive according to claim 5, wherein the or eachcollecting scoop is mounted in the input element at a gap between theinput and output elements.
 7. A hydrodynamic power drive according toclaim 6, herein the end of the collecting scoop is adjacent an innerwall surface of an input element casing structure.
 8. A hydrodynamicpower drive according to claim 1, wherein each outlet discharges into atube or chamber leading into a radially inner portion of a casingstructure which rotates with the input element.
 9. A hydrodynamic powerdrive according to claim 1, having a plurality of collecting scoopswherein some of the collecting scoops face in the opposite direction ofrotation to the other collecting scoops.